Independent presidential candidate Simba Makoni addresses supporters during the launch of his election campaign at White City Stadium in Bulawayo. Photograph: Emmanuel Chitate/Reuters

Zimbabwe's former finance minister has already made history by mounting the most serious challenge from within the Zanu-PF elite to Mugabe. In February, he announced his intention to stand as an independent in the presidential election.

Makoni, 57, became Zimbabwe's youngest cabinet minister when appointed in 1982, aged 32. He was fired by Mugabe in 2002 after differences over economic policy, including calls by Makoni to devalue Zimbabwe's currency.

Makoni has long been touted as a possible successor, although critics say he lacks the mettle to best one of Africa's toughest leaders.

Makoni has some powerful supporters and has been linked to a powerful Zanu-PF faction led by former army commander, General Solomon Mujuru, the husband of vice-president, Joyce Mujuru. However, as a technocrat and business consultant, he has no broad grassroots base and has no supporters contesting parliamentary seats, which are also up for grabs in the March 29 election.

Analysts claim Makoni's chances of defeating Mugabe remain slim. According to some Machiavellian rumours, Makoni is standing in order to split the opposition vote in preparation for the time when he will inherit Mugabe's mantle.